This invention relates to substituted pyrrolidones and to their use in herbicidal formulations. In particular, this invention relates to substituted 1,3-diphenyl pyrrolidones of the formula ##STR2## in which: m is 1, 2, 3, 4 or 5;
n is 0, 1, 2, 3, 4 or 5; PA1 `R' is a member selected from the group consisting of halogen, trifluoromethyl, cyano, C.sub.1 -C.sub.4 alkyl and C.sub.1 -C.sub.4 alkoxy, and, when m is greater than 1 may be either a single such member or a combination thereof: PA1 `R.sup.2 is a member selected from the group consisting of H and halogen: R.sub.3 is a member selected from the group consisting of PA1 halogen trifluoromethyl, cyano, C.sub.1 -C.sub.4 alkyl and C.sub.1 -C.sub.4 alkoxy, and, when n is greater than 1, may be either a single such member or a combination thereof: and PA1 R.sup.4 is a member selected from the group consisting of C.sub.1 -C.sub.4 alkyl and halogen-substituted C.sub.1 -C.sub.4 alkyl.
The compounds of the present invention, as will be seen from the description and test data which follows, have utility as both pre-emergence and post-emergence herbicides, against a wide range of plant species. These compounds are of particular utility in the control of weeds associated with rice crops, notably upland rice. Preferred methods of application to rice crops are post-emergence pre-flood application and pre-emergence spray application.
The terms "herbicide" and "herbicidal" are used herein to denote the inhibitive control or modification of undesired plant growth. Inhibitive control and modification include all deviations from natural development such as, for example, total killing, growth retardation, defoliation, desiccation, regulation, stunting, tillering, stimulation, leaf burn, and dwarfing. The term "herbicidally effective amount" is used to denote any amount which achieves such control or modification when applied to the undesired plants themselves or to the area in which these plants are growing. The term "plants" is intended to include germinant seeds, emerging seedlings and established vegetation, including both roots and above-ground portions.